The present invention relates to a device for coupling a wheel to its shaft which allows an initial relative keying therebetween in both the annular and axial directions. The invention more particularly concerns a device of this type for associating in particular the steering wheel of an automobile steering system with the shaft of the steering column carrying the steering wheel.
For certain applications, it is necessary to be able to choose the initial relative keying in both the angular and axial directions of a wheel on its shaft. This is the case in the automobile field.
As is known, a steering wheel serving to drive an automobiles is generally fixed on the shaft of the steering column by means of splines associated with screw threads and cones. This permits transmitting without play the torque developed by the driver of the automobile to the steering road wheels. Some steering wheels are constructed in the form of a single-piece member and others are directly welded to the shaft.
For reasons of aesthetics and also pleasant conditions of operation, it is necessary to be able to choose and fix at the moment of the construction of the vehicle the initial relative keying in both the angular and axial directions of the steering wheel on its shaft.
Such an initial angular keying serves to cause the position of the steering road wheels of the vehicle, corresponding to straight-ahead steering, to coincide with the symmetrical position of the branches of the steering wheel relative to a plane parallel to the longituddinal median plane of the vehicle. Indeed, it is disagreable, and even sometimes a hindrance for the driver, when the steering road wheels are oriented for the straight-ahead direction of the vehicle and the steering wheel is not exactly in a comparable angular position. As is known, this is difficult to achieve directly upon manufacture and the techniques at present employed do not permit a convenient final adjustment upon assembly.
Furthermore, for reasons of presentation, it is necessary to be able to provide a certain clearance between the lower part of the steering wheel and the casing of the driving station, whence the need for an axial keying possibility. All this is difficult to achieve systematically bearing in mind the tolerances of the dimensions of the component parts and those of the dimensions resulting from the final assembly of the parts at the driving station.
Thus, it will be understood that it is necessary to have a possibility of ensuring such an angular and/or axial adjustment of the steering wheel on its shaft, which has nothing to do with the adjustment of the steering station which exists on certain high-class vehicles for taking into account the ergonomics associated with the driver, his driving style and the geometry of the compartment and seats.
The conventional method usually employed for solving this problem makes use of elongated splines and a shaft or a split hub and a conical support which permits strongly urging a splined and split member onto a massive member. This type of arrangement presents drawbacks since it requires the use of additional members, a machining of high precision of cones to obtain a correct fitting together and an angular fitting which is not progressive since it is related to the pitch of the splines.
When it is desired to have a progressive fitting, it is necessary to avoid the limitations of the pitch of the splines and it is then necessary to interpose an intermediate system; this increases the cost of the component parts and labour for the assembly.